TWI671557B - Backlight module - Google Patents

Abstract

A backlight module includes a light source, a metal back plate, a light guide plate, and a quantum dot film. The metal backboard bag has a bearing surface. The light guide plate is located on the bearing surface of the metal back plate, and includes a light incident surface and a plurality of non-light incident surfaces. The light source corresponds to the light incident surface, and there is a gap between the light incident surface and the light source. The quantum dot film is disposed on the light guide plate. The quantum dot film includes a body, an extension portion, and a plurality of bent portions. The body is located on the light guide plate. The extension portion extends from the body toward the light source direction. On the first projection plane parallel to the body, the extension portion overlaps the light source portion. The bent portions extend toward the direction other than the light incident surface. The bent portion and the non-light incident surface are respectively overlapped on a second projection plane perpendicular to the first projection plane. The bent portion does not contact the bearing surface of the metal back plate.

Description

Backlight module

The present application relates to the field of displays, and in particular to a backlight module.

In the backlight module of the existing liquid crystal display, the quantum dot film can be used to excite the quantum dots with blue light, and then the quantum dots can emit red light, green light, etc., so as to achieve a wider color gamut standard.

However, moisture and oxygen diffuse from the side wall of the quantum dot film, which may cause the quantum dot to fail. Quantum dot failure usually occurs first in the edge of the quantum dot film. This phenomenon may cause the incident blue light to not directly react with the quantum dot and pass directly. Therefore, a blue halo condition is seen at the edge of the active area of the display. With the narrow bezel and even bezel-less design of the display, the problem of blue light appearing at the edge of the active area of the display will have a greater and greater impact on the color gamut of the entire display.

Here, a backlight module is provided. The backlight module includes a light source, a metal back plate, a light guide plate, and a quantum dot film. The metal backboard bag has a bearing surface. The light guide plate is located on the bearing surface of the metal back plate, and includes a light incident surface and a plurality of non-light incident surfaces. The light source corresponds to the light incident surface, and there is a gap between the light incident surface and the light source. The quantum dot film is disposed on the light guide plate. The quantum dot film includes a body, an extension portion, and a plurality of bent portions. The body is located on the light guide plate. The extension portion extends from the body toward the light source direction. On the first projection plane parallel to the body, the extension portion overlaps the light source portion, and the bent portions extend toward the non-light incident surface, respectively, in a direction perpendicular to the first projection plane. The bent portion and the non-light-incident surface are respectively stacked on the second projection plane; wherein the bent portion does not contact the bearing surface of the metal back plate.

In some embodiments, the length of the extension is represented by the following equation (a), equation (a): , Where A is the length of the extension, A ₁ is the length of the gap, A ₂ is the length of the light source, Ly is the width of the light guide plate, δ _LGP is the thermal expansion coefficient of the light guide plate, δ _QD is the thermal expansion coefficient of the quantum dot film, △ T is the temperature change value.

In some embodiments, the bent portions respectively shield the non-light incident surface.

Further, in some embodiments, the bending portion includes a first bending portion and two second bending portions, the first bending portion is located on an opposite side of the extending portion, and the two bending portions are respectively connected to the first bending portion and The length of the extension, the first bend is represented by the following equation (2), and the length of the second bend is represented by the following equation (3): Equation (2): , Equation (3): Where a ₁ is the length of the first bent portion, a ₂ is the length of the second bent portion, Lx is the length of the light guide plate, Lz is the thickness of the light guide plate, δ _LGP is the thermal expansion coefficient of the light guide plate, and δ _QD is The thermal expansion coefficient and ΔT of the quantum dot film are temperature change values.

Further, in some embodiments, each second bending portion includes a creasing line, and the creasing line extends along a width direction parallel to the light guide plate. In other embodiments, each second bending portion includes a plurality of creasing lines, and the creasing lines extend along a width direction parallel to the light guide plate.

In some embodiments, the bent portions are respectively adhered to the non-light incident surface of the light guide plate.

In some embodiments, the backlight module further includes a reflective sheet and an optical sheet, the light guide plate is located on the reflective sheet, and the optical sheet is located on the quantum dot film.

Further, in some embodiments, the backlight module further includes a backlight frame. The backlight frame includes a side wall and an extension wall. The metal back plate further has a side wall, and the side wall extends from one end of the bearing surface in a direction parallel to the thickness of the light guide plate. The side wall is connected with the side wall of the metal back plate. The light source is arranged on the side wall of the metal back plate. The side wall of the backlight frame extends in a direction parallel to the thickness of the light guide plate. The extension wall connects the side wall and extends in a direction perpendicular to the thickness of the light guide plate. A part of the quantum dot film and the optical sheet are located between the bottom plate and the extension wall.

Furthermore, in some embodiments, the metal back plate includes a bolt groove, and the side wall of the backlight frame includes a hook, and the hook is engaged with the bolt groove, so that the metal back plate has a coplanar surface with the side wall.

In summary, the backlight module ensures that the extension of the quantum dot film overlaps with the projection of the light source in the vertical direction during thermal expansion and contraction through the extension of the quantum dot film. At the same time, the bend of the quantum dot film is bent to The light incident surface is not connected to the metal back plate at the bottom. Therefore, the blue light leakage of the light source is avoided, and the phenomenon that the edge of the active area of the display is blue is prevented, and the color gamut and color balance of the display are ensured.

In the drawings, the widths of some elements, regions, etc. are exaggerated for clarity. Throughout the description, the same reference numerals denote the same elements. It will be understood that when an element such as is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element, or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intervening elements present.

It should be understood that, although the terms "first," "second," "third," etc. may be used herein to describe various elements, components, regions, or sections, these elements, components, regions, and / or sections are not Should be limited by these terms. These terms are only used to distinguish one element, component, region, or section from another element, component, region, layer, or section. Thus, a "first element," "component," "region," or "portion" discussed below may be termed a second element, component, region, or portion without departing from the teachings herein.

In addition, relative terms such as "lower" or "bottom" and "upper" or "top" may be used herein to describe the relationship of one element to another element, as shown. It should be understood that relative terms are intended to include different orientations of the device in addition to the orientation shown in the figures. For example, if the device in one of the figures is turned over, elements described as being on the "lower" side of other elements would then be oriented on "upper" sides of the other elements. Thus, the exemplary term "down" may include orientations of "down" and "up", depending on the particular orientation of the drawings. Similarly, if the device in one of the figures is turned over, elements described as "below" other elements would then be oriented "above" the other elements. Thus, the exemplary terms "below" or "below" may include orientations above and below.

FIG. 1 is a schematic cross-sectional view of a backlight module of a first embodiment in a first direction. FIG. 2 is a schematic cross-sectional view of the backlight module of the first embodiment in a second direction. FIG. 3 is a partial top view of the backlight module of the first embodiment before being bent. Here, the first direction is approximately the A-A direction in FIG. 3 and the first direction is approximately the B-B direction in FIG. 3.

As shown in FIGS. 1 to 3, the backlight module 1 includes a light source 10, a light guide plate 20, a quantum dot film 30, and a metal back plate 40. The metal back plate 40 includes a bearing surface 41 and a side wall 43. The light source 10 is disposed on the side wall 43. The side wall 43 extends vertically from one side of the bearing surface 41. The light guide plate 20 is disposed on the bearing surface 41. The light guide plate 20 includes a light incident surface 21 and a plurality of non-light incident surfaces 23 and 25. The light source 10 corresponds to the light incident surface 21, and there is a gap G between the light incident surface 21 and the light source 10. The quantum dot film 30 is disposed on the light guide plate 20. The quantum dot film 30 includes a main body 31, an extension portion 33, and a plurality of bent portions 35 and 37. The main body 31 is located on the light guide plate 20, and its projection in the vertical direction substantially overlaps the light guide plate 20. The extending portion 33 extends from the body 31 in the direction of the light source 10.

As shown in FIG. 1, on the first projection plane P1 of the parallel body 31, the extending portion 33 is partially overlapped with the light source 10. As shown in FIG. 2, the bent portions 37 respectively extend in the direction of the non-light incident surface 23, and the bent portions 37 and the non-light incident surface 25 are stacked on a second projection plane P2 perpendicular to the first projection plane P1. Although not shown in the figure, it can be understood that the bent portion 35 and its corresponding non-light incident surface 23 are also provided in the same manner as described above. In addition, the bent portions 35 and 37 do not contact the bearing surface 41 of the metal back plate 40.

Here, the length of the extension 33 is represented by the following equation (1) and equation (1): , Where A is the extended length of the portions 33, A ₁ is the length of the gap G, A ₂ is the length of the light source 10, Ly is the width of the light guide plate 20, δ _LGP coefficient of thermal expansion of the light guide plate 20, δ _QD quantum dot film The thermal expansion coefficient and ΔT of 30 are temperature change values.

Here, the light source 10 may be a blue light emitting diode to excite the quantum dots in the quantum dot film 30 to generate red light and green light, so as to meet the color standard of a wide color gamut. In addition, the operating temperature of the general backlight module 1 is 25 ° C to 40 ° C at room temperature. The maximum length of the extension portion 33 can be set by setting ΔT to 15 ° C. In this way, it can ensure that the extension portion 33 and the light source are thermally expanded. 10 Overlapping projections in the vertical direction can avoid the leakage of the edges of the blue light to ensure the color gamut and color balance of the display.

As shown in FIGS. 1 and 2, in some embodiments, the backlight module 1 further includes a reflective sheet 51 and an optical sheet 53. The light guide plate 20 is located on the reflection sheet 51, and the optical sheet 53 is located on the quantum dot film 30. The reflection sheet 51 is usually white to reflect the ambient light or other inwardly reflected and refracted light to the light guide plate 20, and the optical sheet 53 can guide the light out of the light guide plate 20.

As shown in FIGS. 1 and 2, in some embodiments, the backlight module 1 further includes a backlight frame 60. The backlight frame 60 includes a side wall 61 and an extension wall 63. The side wall 61 is connected to the side wall 43 of the metal back plate 40. The side wall 43 of the metal back plate 40 and the side wall 61 of the backlight frame 60 extend in a direction parallel to the thickness of the light guide plate 20. The extension wall 63 is connected to the side wall 61 and extends in a direction perpendicular to the thickness of the light guide plate 20. The light source 10, a part of the light guide plate 20, a part of the quantum dot film 30, a part of the reflection sheet 51, and a part of the optical sheet 53 are located between the bearing surface 41 of the metal back plate 40 and the extension wall 63 of the backlight frame 60.

In this way, the extension wall 63 can prevent the light emitted from the light source 10 from directly passing through the side, which can reduce the chance of light leakage and ensure the color gamut and color balance of the display. Furthermore, the backlight frame 60 may be black, so as to absorb the light leaked from the light guide plate 20 and reduce the chance of light leakage.

As shown in FIG. 3, the bent portions 35 and 37 can be divided into a first bent portion 35 and two second bent portions 37. The first bending portion 35 is located on the opposite side of the extending portion 33, and the two second bending portions 37 are connected to the first bending portion 35 and the extending portion 33, respectively. In addition, as shown in FIG. 1 and FIG. 2, the second bending portion 37 shields the non-light incident surface 25 respectively. It can be understood that although not shown in the figure, the first bending portion 35 is also shielded in the other direction.非 Entering surface 23. Furthermore, the first bending portion 35 and the second bending portion 37 may be adhered to the non-light-entering surfaces 23 and 25 of the light guide plate 20 through the adhesive layer 70, and the first bending portion 35 and the second The bent portion 37 is not in contact with the metal back plate 40. In this way, it is ensured that the light emitted from the side of the light guide plate 20 can excite the quantum dots in the quantum dot film 30 first, and the sides of the quantum dot film 30 are bent to reduce the penetration of water vapor and air, even the quantum The quantum dots in the dot film 30 have a problem of failure. The edge positions of the quantum dots are bent and located in the invalid area, which will not directly affect the color gamut in the active area of the display area.

As shown in FIG. 1 to FIG. 3, in order to prevent blue light from being transmitted through the non-light incident surfaces 23 and 25, as with the light incident surface 21, the problem of thermal expansion and contraction must be considered. The length of the first bent portion 35 is represented by the following equation (2), and the length of the second bent portion 37 is represented by the following equation (3). Equation (2): , Equation (3): Where a ₁ is the length of the first bent portion 35, a ₂ is the length of the second bent portion 37, Lx is the length of the light guide plate 20, Lz is the thickness of the light guide plate 20, and δ _LGP is the thermal expansion of the light guide plate 20. The coefficient and δ _QD are thermal expansion coefficients of the quantum dot film 30, and ΔT is a temperature change value. In this way, it is ensured that the first bent portion 35 and the second bent portion 37 can completely shield the non-light incident surfaces 23 and 25 during thermal expansion and contraction.

FIG. 4 is a partial top view of the backlight module before being bent according to the second embodiment. 5 is a schematic cross-sectional view of a backlight module in a second direction according to a second embodiment. As shown in FIG. 4, the second bending portion 37 of the quantum dot film 30 includes a creasing line 371 extending along a width direction parallel to the light guide plate 20, that is, extending along the non-light incident surface 25. Direction. As shown in FIG. 5, after bending, a bump can be generated, thereby ensuring length adjustment during thermal expansion and contraction, and also avoiding light leakage.

FIG. 6 is a partial top view of the backlight module before being bent according to the third embodiment. FIG. 7 is a schematic cross-sectional view of a backlight module of a third embodiment in a second direction. As shown in FIG. 6, the second bending portion 37 of the quantum dot film 30 includes a plurality of fold lines 371, and the fold lines 371 extend in a width direction parallel to the light guide plate 20. As shown in FIG. 7, after bending, a zigzag structure can be generated, thereby ensuring the length adjustment during thermal expansion and contraction, and also achieving the effect of avoiding light leakage.

8 is a top view of an embodiment of a backlight module in a second direction. FIG. 9 is a bottom view of an embodiment of a backlight module in a second direction. As shown in FIGS. 8 and 9, in some embodiments, the side surface 45 of the metal back plate 40 is provided with a bolt groove 451, and the side wall 61 of the backlight frame 60 further includes a hook 611. The hook 611 is engaged with the bolt groove 451, so that the side surface 45 of the metal back plate 40 is coplanar with the side wall 61, and the effect of thinning the periphery of the display can be achieved. Further, although it is not shown in the figure, it can be understood that, in this embodiment, the side wall 43 of the metal back plate 40 can be omitted, and the light source 10 can be directly installed on the side wall 61 to achieve an extremely narrow frame effect. Here, the metal back plate 40 may have a step, and the bolt groove 451 and the hook 611 may be one or more, and their shapes and sizes may also be different. The diagram is only an example, not a limitation. Various connection modes that generate coplanarity are applicable.

To sum up, the backlight module 1 extends the projection 33 of the quantum dot film 30 to ensure that the projections of the extension 33 and the light source 10 overlap with each other when the thermal expansion and contraction occur. At the same time, the quantum dot film 30 The bent portions 35 and 37 are bent to the non-light incident surfaces 23 and 25 and are not connected to the bottom metal back plate 40. Therefore, the blue light leakage of the light source 10 is avoided, and the phenomenon of blue light at the edges of the active area of the display is prevented, and the color gamut and color balance of the display are ensured.

Although the technical content of the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art and making some changes and retouching without departing from the spirit of the present invention should be covered by the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the appended patent application.

1‧‧‧ backlight module

10‧‧‧ light source

20‧‧‧light guide

21‧‧‧Into the light surface

23‧‧‧ non-glossy surface

25‧‧‧Non-light surface

30‧‧‧ Quantum Dot Film

31‧‧‧ Ontology

33‧‧‧ extension

35‧‧‧ Bend section (first bend section)

37‧‧‧ Bending section (second bending section)

371‧‧‧Folding line

40‧‧‧ metal back plate

41‧‧‧bearing surface

43‧‧‧Side wall

45‧‧‧ side surface

451‧‧‧bolt groove

51‧‧‧Reflector

53‧‧‧Optical sheet

60‧‧‧ backlight frame

61‧‧‧ sidewall

611‧‧‧ Hook

63‧‧‧extended wall

70‧‧‧ Adhesive layer

A‧‧‧ extension length

A ₁ ‧‧‧ length of the gap

A ₂ ‧‧‧ length of light source

a ₁ ‧‧‧ the length of the first bend

a ₂ ‧‧‧ Length of the second bend

Lx‧‧‧ length of light guide plate

Ly‧‧‧ the width of the light guide plate

Lz‧‧‧ thickness of light guide plate

G‧‧‧ Clearance

P1‧‧‧first projection plane

P2‧‧‧second projection plane

FIG. 1 is a schematic cross-sectional view of a backlight module of a first embodiment in a first direction. FIG. 2 is a schematic cross-sectional view of the backlight module of the first embodiment in a second direction. FIG. 3 is a partial top view of the backlight module of the first embodiment before being bent. FIG. 4 is a partial top view of the backlight module before being bent according to the second embodiment. 5 is a schematic cross-sectional view of a backlight module in a second direction according to a second embodiment. FIG. 6 is a partial top view of the backlight module before being bent according to the third embodiment. FIG. 7 is a schematic cross-sectional view of a backlight module of a third embodiment in a second direction. 8 is a top view of an embodiment of a backlight module in a second direction. FIG. 9 is a bottom view of an embodiment of a backlight module in a second direction.

Claims (10)

A backlight module includes: a light source; a metal back plate with a bearing surface; a light guide plate on the bearing surface of the metal back plate, including a light incident surface and a plurality of non-light incident surfaces, wherein the light source Corresponding to the light incident surface, there is a gap between the light incident surface and the light source; and a quantum dot film disposed on the light guide plate, the quantum dot film includes a body, an extension portion, and a plurality of bending portions , The body is located on the light guide plate, the extension part extends from the body toward the light source, on a first projection plane parallel to the body, the extension part overlaps with the light source part, and the bending parts Do not extend in the direction of the non-light-incident surfaces, and the bent portions and the non-light-incident surfaces are respectively overlapped on a second projection plane perpendicular to the first projection plane; wherein, the bends The part does not contact the bearing surface of the metal back plate. The backlight module according to claim 1, wherein the length of the extension is expressed by the following equation (1): Equation (1):

, Where A is the length of the extension, A _{1 is} the length of the gap, A _{2 is} the length of the light source, Ly is the width of the light guide plate, δ _{LGP is} the thermal expansion coefficient of the light guide plate, and δ _{QD is} the quantum dot The thermal expansion coefficient and ΔT of the film are the temperature change values. The backlight module according to claim 1, wherein the bent portions respectively shield the non-light incident surfaces. According to the backlight module of claim 3, the bending portions include a first bending portion and two second bending portions, the first bending portion is located on the opposite side of the extending portion, and the two second bending portions The folded portion is connected to the first bent portion and the extended portion, wherein the length of the first bent portion is represented by the following equation (2), and the length of the second bent portions is represented by the following equation (3). two):

, Equation (3):

Where a ₁ is the length of the first bent portion, a ₂ is the length of the second bent portion, Lx is the length of the light guide plate, Ly is the width of the light guide plate, Lz is the thickness of the light guide plate, δ _{LGP is} the thermal expansion coefficient of the light guide plate, δ _{QD is} the thermal expansion coefficient of the quantum dot film, and ΔT is the temperature change value. The backlight module according to claim 4, wherein each of the second bending portions includes a creasing line, and the creasing line extends along a direction parallel to the width of the light guide plate. The backlight module according to claim 4, wherein each of the second bending portions includes a plurality of creasing lines, and the crimping lines extend parallel to the width direction of the light guide plate. The backlight module according to claim 1, wherein the bent portions are respectively adhered to the non-light incident surfaces of the light guide plate. The backlight module according to claim 1, further comprising a reflective sheet and an optical sheet, the light guide plate is located on the reflective sheet, and the optical sheet is located on the quantum dot film. The backlight module according to claim 8, further comprising a backlight frame, the backlight frame includes a side wall and an extension wall, the metal back plate further has a side wall, the side wall is parallel along one end of the bearing surface Extending in the direction of the thickness of the light guide plate, the side wall is assembled with the side wall of the metal back plate, the light source is disposed on the side wall, the side wall extends in a direction parallel to the thickness of the light guide plate, the extension The wall is connected to the side wall and extends in a direction perpendicular to the thickness of the light guide plate. The light source, the reflection sheet, the light guide plate, the quantum dot film, and a portion of the optical sheet are located between the base and the extension wall. The backlight module according to claim 9, wherein the metal back plate includes a bolt groove, and the side wall of the backlight frame includes a hook, and the hook is engaged with the bolt groove so that the metal back plate is connected to the The side walls are coplanar.